EFFECT OF TEMPERATURE, NITROGEN FERTILIZATION AND MOISTURE STRESS ON YIELD, YIELD COMPONENTS, PROTEIN CONTENT AND MOISTURE USE EFFICIENCY OF MANITOU SPRING WHEAT

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Abstract
The effects of temperature, nitrogen fertility (N), and moisture stress on the yield components, protein content and moisture use efficiency of Manitou wheat (Triticum aestivum L.) were determined under simulated irrigation in a 2 × 3 × 5 factorial experiment. Grain yield was directly related to and mainly influenced by N. Yield was directly related to the number of spikes (r = 0.71**), and the number of seeds/spike (r = 0.65**), and inversely related to average seed weight (r = −0.41**). Seed weight was also inversely related to the number of spikes and number of seeds per spike. At maturity, the number of spikes was directly and mainly affected by N. The number of spikelets per spike, seed set of primary and secondary florets, and seed weight were inversely related to, and mainly a function of, temperature. At high temperature and low NO3-N, low moisture stress was detrimental to several yield components where these conditions existed during a period critical to the development of the component. These poor responses were alleviated by high moisture stress or high rate of NO3-N fertilizer or both. Grain protein was mainly influenced by temperature to which it was directly related. Protein was increased by N at day/night temperatures of T22/12 °C, but was unaffected by N at T27/12 °C; it was also increased by high moisture stress applied between last leaf visible and anthesis. Grain protein was inversely related to grain yield at any given level of N. Covariance was used to isolate the true effect (i.e., corrected for yield effects) of the treatment variables on protein. In this experiment, N influenced protein only via its effect on grain yield. Moisture use efficiency for grain production was improved by all factors that increased grain yield (e.g., increased N, low temperature, or high moisture stress between tillering and last leaf visible). Efficiency was deleteriously affected by moisture stress between last leaf visible and anthesis.